// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
#define CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_

#include <memory>
#include <string>

#include "base/macros.h"
#include "content/common/content_export.h"
#include "media/capture/content/screen_capture_device_core.h"
#include "media/capture/video/video_capture_device.h"

namespace content {

// A virtualized VideoCaptureDevice that captures the displayed contents of a
// WebContents (i.e., the composition of an entire render frame tree), producing
// a stream of video frames. As such, WebContentsVideoCaptureDevice is only
// supported on platforms that use the Chromium compositor, have a
// content::RenderWidgetHostView implementation that supports frame subscription
// (via BeginFrameSubscription()), and can perform read-back into
// media::VideoFrames (i.e.,
// RenderWidgetHostViewBase::CopyFromCompositingSurfaceToVideoFrame() is
// functional).
//
// An instance is created by providing a device_id.  The device_id contains
// information necessary for finding a WebContents instance.  From then on,
// WebContentsVideoCaptureDevice will capture from the RenderWidgetHost that
// encompasses the currently active RenderFrameHost tree for that that
// WebContents instance.  As the RenderFrameHost tree mutates (e.g., due to page
// navigations, or crashes/reloads), capture will continue without interruption.
class CONTENT_EXPORT WebContentsVideoCaptureDevice
    : public media::VideoCaptureDevice {
public:
    // Create a WebContentsVideoCaptureDevice instance from the given
    // |device_id|.  Returns NULL if |device_id| is invalid.
    static std::unique_ptr<media::VideoCaptureDevice> Create(
        const std::string& device_id);

    ~WebContentsVideoCaptureDevice() override;

    // VideoCaptureDevice implementation.
    void AllocateAndStart(const media::VideoCaptureParams& params,
        std::unique_ptr<Client> client) override;
    void RequestRefreshFrame() override;
    void MaybeSuspend() override;
    void Resume() override;
    void StopAndDeAllocate() override;
    void OnUtilizationReport(int frame_feedback_id, double utilization) override;

private:
    WebContentsVideoCaptureDevice(
        int render_process_id,
        int main_render_frame_id,
        bool enable_auto_throttling);

    const std::unique_ptr<media::ScreenCaptureDeviceCore> core_;

    DISALLOW_COPY_AND_ASSIGN(WebContentsVideoCaptureDevice);
};

} // namespace content

#endif // CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
